The basic objective is to carry forward the operational analysis of language and to explicate the cognitive preconditions for language. The principal subjects are chimpanzees although selected topics will be carried out on other species including young children, Cebus monkeys, dogs, and pigeons. Two language systems are used with naive and sophisticated subjects respectively. In the former, metal-backed pieces of plastic serve as words; sentences are produced by placing the words in vertical arrays on a magnetic board. In the latter, each key on a keyboard is marked with a picture of a plastic word; when the key is operated a corresponding visual representation appears on a colored TV monitor. In addition to teaching the basic exemplars of language, special attention is given to those aspects of language which are most revealing for thinking and internal representation. Cognitive preconditions include rule induction, studied through recognition tests on the partial content of matrices; the effect of hierarchical memory structure on the order of what is learned; and the conceptual structure underlying language.